Tellurium

Formation and reactions of Dewar 4-pyrimidinones in the photochemistry of 4-pyrimidinones at low temperature. 2

“…The volume of the solvents was about 230 raL. 6 The yields were estimated by integration of the peak areas of the 'H NMR spectra. °Reference 3.…”

“…The ratios of 1 and 2 were estimated by integration of the peak areas of the 'H NMR spectra. 6 C, CH3OH; D, CH3ONa-CH3OH (0.05-0.1 M). The solution of 2 in 100-230 mL was stored at -20-0 °C for 1-7 days.…”

“…0 CH3ONa-CH3OH (0.053 M, 350 mL). 6 The yield was corrected for the recovered starting material. 0 Recrystallization of 5d from benzene-methanol gave 17 (68%).…”

“…The product 7d is produced by the addition of the nucleophile to the imine bond of 2d, but the acetal 8d is not. Another initial reaction (SN2) which competes with the addition reaction occurs by attack of methoxide anion on the bridgehead C(l) with concomitant cleavage of C(l)-N (6) bond to give 14, which leads to the formation of the acetal 8 (Scheme IV).…”

“…In order to confirm the reaction mechanism, we studied the photochemistry of the imino ethers 5a-c in CD30-Na-CD3OD and in CD3OD. When the imino ether 5c [X( MeOH) 266 nm (e 1.22 X 104)] in methanol-d4 containing sodium methoxide-d3 (0.02 M) was irradiated through a Corning glass filter (X > 220 nm) at 254 nm in a quartz NMR tube at 20-25 °C, new signals in XH NMR spectrum appeared at 6 3.55 (s, 3 H) and 6.37 (s, 1 H) which were assigned to the 2V-methyl and olefinic protons of the 4-pyrimidinone 9c (=lb). The protons of the 2-methyl group were observed as a small signal due to the H/D exchange under the reaction conditions.…”